Production of electric waves



May 5, 1931.

H. E. HOLLMANN PRODUCTION OF ELECTRIC WAVES Filed June 20, 1929Invenfor.

Hans Erich Hellman/1 Patented May 5,1931

PA T FI E HANS ERICI-I HoLLMAnN, or DARMSTADT, GERMANY y I PRODUCTION OFELECTRIC 1 Application filed June 20, 1929, Serial No. 372,406, and inGermany June 4,1928;

Application for this invention filed in Germany, J une4, 1928.

My invention refers to the production of electric waves and moreespecially to means 1 whereby short electric waves can be produced bymeans of electron oscillation;

As a rule electric oscillations are produced by means of electron tubes1n regenerative connection, the circuits ofthe grid and anode ofa threeelectrode valve being coupled with each other in such manner thatoscillation energy is constantly fed back and all losses of Thefrequency remains absolutely constant throughout the building up of theoscillations to their resonance amplitude.

This process is not adapted for the production of very short wavesbecause the time of transit of the electrons within the tube isnotnegligible any more as compared with the duration .of the periods ofoscillation. In

,consequencethereof feed-back conditions, especially as far as theyconcern the position of the phases of the alternate potential at thegridand the anode, 'cannot be satisfied any more. I V 5 7 Very shortwaves can be produced accord-' ing to the method suggested by Barkhausenand Kurz. In thisknown process the time,

during which the electrons remain in the,

space between'the' electrodes, determines the frequency, in that apendulum movement of the electrodes relativeto the grid takes place byproviding means for a particular field,

distribution differing essentially from the usual operation of vacuumtube. To this end the grid is imparted a high positive, the anode a'lownegative potential; The electrons passing'through the grid with highvelocity are returned by the brakingfield of the anode and pass againthrough the grid, whereupon the same phenomenon starts able along thesewires. I

mined by the theoretical formula:

all over againi Barkhausen and Kurz found that the wave length dependsmerely upon the electric field intermediatethe electrodes andthat anoscillatory system connected with the tube does not influence thefrequency but merely increases the oscillation energy.

I have now found that if an 'oscillatorysystem coupledwith'the tube issuitably tuned,

the frequency will jump suddenly as the wave 1 length of the pendulummotion of the electronsinerges into the natural wave length of thetuning system. 7 1 r In the drawings affixed to this specification andforming part thereof, a diagram-illustrating this invention is shown by,way of eX- ampl. In this diagram R representsflm tube, having an anodeF, a grid G, and a'cathode H. a

The grid and anode are connected'withtwo.

parallel Wires L and L, respectively, .and B is a bridging condenserwhich is displace To different positions of the-condenser B correspondthe" wave 7 lengths shown by the curve. The jump, by whichthelBarkhausen- Kurz frequency merges into the natural wave lengthoft-he parallel'wire system, is K made visible at A. These jumps offrequency are probably caused by the circumt stance that the electronsswinging between vthe electrodes exclte the outer oscillation system, sothat the alternating potentials of V the oscillating system are"superimposed upon the direct current potentials of the tube electrodes.These alternating potentials now react on the exciting electron os-y Vcillations in a manner toincrease 'theirfre- 1 quency. The wavelength ofthe electron oscillations, if any alternating potential E issuperimposed upon'the direct current-potential E of the grid electrode,

wherein 03 represents the distance between the electrodes. l The formulashows that is gradually is deter-' loo shortened in proportion to theincrease of E as can be guessed from the following numerical example:

If E =5OO volt and d=0,5 cm., E and A are found to have the followingvalues:

E, 0 100 200 300 400 Volt A 89,5 86,9 82,5 74,6 58,8 cm.

Now if the natural wave length of the tuning system is less than thewave length of Barkhausen-Kurz the exciting electron frequency, inconsequence of the alternating potentials tials of the electrode, willapproach the resonance wave length of the wire system. This results inan increase of the alternating potentials, whereby the exciting wavelength is further shortened and approaches further the resonance wavelength. Obviously in this manner a frequency rise is obtained wherebythe frequency will increase until it attains the natural frequency ofthe oscillatory wire circuit. A proper increase of the excitingfrequency beyond resonance would result in a weakening of thealternating field and consequently a decrease of the oscillations.

The present invention is thus based on the fact that the electronsswinging between the electrodes are received from the alternatingfields, which they themselves have induced, an increase of frequency,whereby a gradual frequency rise is brought about. This phenomenon maybe compared to the phenomena occurring in feed-back systems in which,however, merely an energy rise at constant frequency takes place. In thepresent case, too, where ultra-short waves are produced, an increase ofenergy is obtained also besides the frequency rise as described.

Various changes may be made in the details disclosed in the foregoingspecification without departing from the invention or sacrificing theadvantages thereof.

In the claims afiixed to this specification no select-ion of anyparticular modification of the invention is intended to the exclusion ofother modifications thereof and the right to subsequently make claim toany modification not covered by these claims is expressly reserved.

I claim:

1. In a system for producing ultra high frequency electric oscillationsby electron pendulum movements within a vacuum space 1n a retardingfield arrangement including an oscillatory system for utilizing saidoscillations, the method of increasing the natural electron oscillatingfrequency determined by the field strength which consists in tuning saidsystem to a frequency greater than said natural frequency of saidelectron movements.

2. In a system for producing ultra high frequency electric oscillationsby electron pendulum movements about the grid electrode of a vacuum tubehaving a high positive potential applied and a wire tuning systemconnected to said grid electrode, the method of increasing the naturalfrequency of the electronic oscillations determined by sald potentialwhich consists in tuning said wire system to a frequency greater thansaid natural frequency.

In testimony whereof I afiix my signature.

HANS ERICH HOLLMANN.

added to the direct current poten-

